Animals as a source of organs and tissues for xenotransplantation could become a backup solution for the growing shortage of human donors. The presence of human xenoreactive anti- bodies directed against Galα1,3Gal antigens on the cell surface of a pig donor triggers the activa- tion of the complement leading to a hyperacute reaction. The development of genetic engineer- ing techniques has enabled the modification of genomes by knocking in and/or knocking out genes. In this paper, we report the generation of modified pigs with ZFN mediated disruption of the GGTA1 gene encoding the enzyme responsible for synthesis of Galα1,3Gal antigens. ZFN plasmids designed to target the exon 9 region of the pig GGTA1 gene encoding the catalytic domain were injected into the pronuclei of fertilized egg cells. Among 107 piglets of the F0 gene- ration analyzed, one female with 9-nt deletion in exon 9 of the GGTA1 gene was found. 13 of 33 piglets of the F1 generation represented the +/- GGTA1 genotype and 2 of 13 F2 piglets repre- sented the -/- GGTA1 genotype. No changes in the animals’ behavior, phenotype or karyotype were observed. Analysis confirmed heredity of the trait in all animals. A complex functional analysis of the modified animals, including flow cytometry, human serum cytotoxicity test and immunohistochemical detection, was performed to estimate the phenotype effect of genetic modification and this indicated an efficient GGTA1 knock-out in modified pigs.
The paper presents the results of the effect of isothermal heating time on the disappearance of strain hardening (the softening degree) of the studied high-manganese TRIPLEX type steels at a temperature of 900 and 1000°C. In order to determine the kinetics of recrystallization of austenite plastically deformed for selected steels, hot compression tests with draft ε = 0.2 were made. The presented results reveal that the complete recrystallization of austenite needs long isothermal heating times. In industrial conditions, such long times are not used, therefore in the initial rolling passages, the time required for half recrystallization of austenite t0.5 is often used. The total disappearance of the strain hardening, completion of the recrystallization of austenite tested high-manganese X98 and X105 TRIPLEX type steels isothermal heating time requires far more than 200 s. The increase of the deformation temperature is a factor influencing the acceleration of the disappearance of strain hardening.
Abstract The paper presents numerical analyses aimed at preliminary assessment of the protective panel effectiveness, which task is to protect the elements of building structures against explosion. For the criterion of assessing the effectiveness of the panel the load capacity of the column made of steel I-beam was chosen. Ultimate force was determined by using advanced computational procedure, which consisted of four stages: preload, blast simulation, dynamic response and static analysis of deformed structure. Blast load was simulated using Lagrangian- Eulerian domain coupling. Results indicated that the application of the protective panel significantly reduces the plastic deformation of the structure.